COLLECTING ECONOMIC PLANT DATA 37 



light bulbs (fig. 29). The box should rest on feet to give a space of an 

 inch or so at the bottom to allow circulation of air. By extending the 

 length of the box, any number of presses may be accommodated. 



When using the sun as the drying agent, or when all the space over 

 the stoves is occupied, the blotters must be changed frequently, at 

 least twice the first day, otherwise the plants will discolor badly, or even 

 mildew and disintegrate, in which case the specimens are practically 

 worthless. The blotters have to be dried out by standing them up against 

 a wall, ,or by spreading them out on the floor or out-of-doors. This 

 method is slow and scarcely practicable, except in dry climates with an 

 abundance of hot sunshine, or when only a few plants are being handled. 



Actually the use of blotters retards the speed of drying, because the 

 heat coming through the corrugations of the cardboards has to pene- 

 trate the blotters before reaching the plants. Consequently, the drying- 

 process could be speeded up by leaving the blotters out of the press and 

 using only the cardboard ventilators between the plants. The method 

 has been used successfully in dry climates for all types of plants. It will 

 serve, also, even in wet climates, for such plants as grasses and sedges, 

 which are not too juicy, provided one has a good quality of smooth- 

 faced cardboards and a dependable source of artificial heat. 



An innovation suitable for tropical climates consists in using cor- 

 rugated aluminum sheets as substitutes for the corrugated-cardboard 

 ventilators. Aluminum conducts heat much more efficiently than card- 

 board, and consequently the plants dry quite rapidly. The aluminum 

 sheets are about ten times more expensive than the cardboard but have 

 the advantage of lasting indefinitely and furthermore of requiring less 

 space when packed. The sheets measure ll 1 ^ by 16 inches, with rounded 

 corrugations 3^8 mcn deep and Yi i ncn from crest to crest, the corruga- 

 tions running crosswise, not lengthwise. The metal should be hard 

 aluminum 0.008 inch thick. A special die is required to make the cor- 

 rugations. 



For drying only a few specimens, when none of the regular equipment 

 is available, various methods can be improvised. The specimens might be 

 placed between pieces of corrugated cardboard, firmly tied with string, 

 and hung over a stove or other source of heat. Layers of folded paper are 

 sometimes used as driers, but usually this method is unsatisfactory and 

 results in ruined or mildewed specimens. Small specimens can be pre- 

 pared by pressing them in magazines having rough, pulp-paper pages. 

 But, even so, the specimens must be watched and changed to new pages 

 to keep them from spoiling. 



Whatever the system used for drying, one needs to have some means 

 of knowing when the process is completed. This stage of dryness is best 

 learned by experience. Most plants when dry, however, will be perfectly 

 rigid when lifted off the sheet. Leaves should break with a snap when bent. 



Fleshy leaves, such as those of orchids, and some types of roots, stems, 

 or fruits often resist drying. If they dent easily when tested with a finger- 

 nail, they need further drying. The process can be hastened by making- 

 several crosswise slits in larger objects with a knife and by merely punc- 

 turing smaller ones with a needle or knife point. 



Grasses and delicate thin-leaved plants should dry completely in less 

 than 8 hours, and the great majority of plants within 24 hours if the 

 heat is constant, day and night. For this reason the press should be 

 examined daily, and those specimens that have dried sufficiently should 



